Scarless tummy tuck?

There is no such thing as a "scarless" tummy tuck.  Any time the skin is cut, there is a scar left behind. Plastic surgeons are trained to hide scars as well as possible, but every surgery leaves a scar.

It is possible that what you heard described is an endoscopic repair of a rectus diastasis or separation of the abdominal muscles. This can be done with very small incisions in the belly button.  But this procedure will not take out over stretched hanging skin.  There is no way to remove skin without leaving a long scar. But the scar of a tummy tuck can heal very nicely and be hidden under a small bikini